18. Pharmacology of the drug influencing sexual function 2. (progestagens, oestrogens, androgens) Flashcards
Natural sex steroid hormones. Production.
Gonads produce limited number of steroids affecting sexual behaviour, secondary sex characteristics, accessory sex organs and reproduction in general.
Cholesterol -› pregnenolone -› progesterone -› testosterone -› oestrogens
Fat-soluble, shortf half-life (minutes)
Common structure in all species
What is the difference between natural and synthetic sex hormones?
Synthetic have increased specificity, increased half-life, increased oral absorption
What are natural oestrogens? Where produced? PK?
- estrone
- estradiol-17 beta
- estriol
Produced by granulosa cells of the ovarian follicle, CL, adrenal cortex, testicles, placenta (large quantity in late pregnancy)
Can be absorbed through skin, mucous membrane, GIT. Metabolism in liver. Elimination primarily in urine
What are the effects of oestrogens?
- development of female sex organs
- development and maintenance of secondary female sex characteristics
- cause ↑ cell height and secretion of the cervical mucosa, endometrial proliferation and ↑ uterine tone
- slight anabolic effect, ↑ Na and water retention, ↑Ca deposition, ossification, ↑epiphyseal closure
- release of GnRH
Side effects of oestrogens:
mainly according to prolonged use or large doses
- in cow: postparturient straining with prolapse of vagina, uterus
- in dog: anaemia, endometritis
- ovarian suppression and hypoplasia -› ovarian cysts
- feminisation in the male
- NOT BE GIVEN to animals with mammary tumours and during pregnancy
Clinical use of oestrogens:
In females:
- to control reproduction
- treatment of uterine infections
- inhibition of nidation - misalliance in the bitch
- to treat urinary in continence and dermatitis in old ovariectomised bitches
- to diminish lactation in bitches and cats
- to treat cattle having persistent CL due to certain cases (in some oestrogen is luteotrophic)
In males:
- anal adenoma, prostate hypertrophy, benign tumor
What oestrogen preparation do we use in clinical practice?
- estriol
- oestradiol benzoate
Progesterone and its physiological role
Main source is corpus luteum
transforms proliferative endometrium to secretory endometrium in pregmamt animals, inhibits uterine contractility
Main uses of natural progesterone in vet practice
- synchronisation
- prevention of embryonic death - not satisfactory
- to delay partuition: not effective
What are progestogens?
Synthetic preparations os progesterone.
Are more effective and have longer duration of action.
What are 2 types of progestogens?
- Strong gestogens (1st generation): MAP, Norgestomet
- Weak gestogens (2ns generation): Proligeston
What is an antiprogestogen drug? What is it used for?
Aglepristone
To terminate pregnancy - abortion
